13.7 billion years ago: The Big Bang Theory (The Universe's Possible Beginnings)

*Planck epoch: From the start to 10-43 seconds after the Big Bang.  Very little concrete information is known about this epoch. Different theories propose different views on this particular time.
*Grand Unification epoch: Between 10-43 to 10-36 seconds after the Big Bang.  The result of the universe expanding and cooling down during the Planck epoch.
*Electroweak epoch: Between 10-36 seconds to 10-12 seconds after the Big Bang.  The universe cools down to 1028 Kelvin.
*Inflationary epoch: Between 10-36 seconds to 10-32 seconds after the Big Bang.  The shape of the universe flattens due to cosmic inflation.
*Quark epoch: Between 10-12 seconds to 10-6 seconds after the Big Bang.  Cosmic inflation has ended. Quarks are present in the universe at this point.
*Hadron epoch: Between 10-6 seconds to 1 second after the Big Bang.  The universe has cooled enough for quarks to form hadrons, protons, neutrons.
*Lepton epoch: Between 1 second to 10 seconds after the Big Bang.  Most hadrons and anti-hadrons annihilate each other, leaving behind leptons and anti-leptons.
*Photon epoch: Between 10 seconds to 380,000 years after the Big Bang.  Most leptons and anti-leptons annihilate each other. The universe is dominated by photons.
*Nucleosynthesis: Between 3 minutes to 20 minutes after the Big Bang.  The temperature of the universe has cooled down enough to allow atomic nuclei to form via nuclear fission.
*Recombination: About 377,000 years after the Big Bang.  Hydrogen and helium atoms form.
*Reionization: Between 150 million and 1 billion years after the Big Bang.  The first stars and quasars form due to [[gravitational collapse.

The cosmological timescale is the longest imaginable. It covers the entire extent of the universe - many billions of years. A short first period is measured in tiny fractions of seconds, but thereafter most things happen on the scale of billion years. It is used to consider events noticeable on a universal scale, such as the formation of matter, stars, and galaxies.
*The Big Bang (13.7 GYA)
*The Dark Age between recombination and reionization (13.7-13.5 GYA)
*The Star-forming Era (13.5 GYA - now)

                  Eon                                    Era                                       Period                                 Epoch                     

        *Milocene Epoch (25 to 5 million years ago), [Tertiary Period, Cenozoic Era, Phanerozoic Eon].  Human evolution began as the Earth's climate started to cool during the Milocene epoch.  During the early Miocene the global climate was warmer than today.  Widespread tropical forests in Africa and Eurasia supported diverse populations of early hominoid apes, including a common ancestor of gorillas, chimpanzees and humans.  By the end of this era ice caps had formed at the Poles, and drier conditions in Africa caused tropical forests to shrink.  In east Africa, the probably birthplace of the hominids, this was exacerbated by geological movements that led to the uplift of the East African plateau and the formation of the Rift Valley.  The ancestral hominids were confined to shrinking "islands" of forests surrounded by open woodland and savanna.  As a result they learned to walk on two legs, allowing them to cover longer distances on the ground. 
        *Pliocene Epoch (5 to 1.8 millions years ago), [Tertiary Period, Cenozoic Era, Phanerozoic Era]. 
        *Pleistocene Epoch (1.8 to .01 million years ago), [Quaternary Period, Cenozoic Era, Phanerozoic Eon].  The human evolution that began during the Milocene epoch culminated about one million years ago during the Pleistocene Epoch. 

Stone Age
    Palaeolithic (Old Stone Age)- 2 million years ago- approx. 10,000 B.C.
    Mesolithic (Middle Stone Age)- 10,000 B.C.-8,000 B.C.
    Neolithic (New Stone Age)- 8,300 B.C.-3,200 B.C.
Copper Age (fairly new division in historical circles)
Bronze Age
    Early Bronze- 3,200-2,200 B.C.
    Middle Bronze- 2,200-1,550 B.C.
    Late Bronze- 1,550-1,200 B.C.
Iron Age
    Iron Age I- 1,200-1,000 B.C.
    Iron Age II- 1,000-586 B.C.